Governments and their associated first responders are increasingly interested in protecting their citizenry from exposure to dangerous levels of radiation that might result from accidental or purposeful release of nuclear materials. In a current high-profile example from recent media reports, the United States Department of Homeland Security suspects terrorist organizations of planning to build and explode a so-called “dirty bomb” in the United States. Less newsworthy, but nevertheless troubling, dangerous nuclear materials are commonly lost or stolen.